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Gray Leaf Spot

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What is Gray Leaf Spot?

Gray leaf spot is a Spring/Summer disease that primarily affects St. Augustine grass but can affect other warm season grasses. Gray leaf spot starts as small lesions on the leaves and stems of grass plants during warm, humid weather. These lesions will grow larger over time with a tan appearance in the middle surrounded by a purplish brown margin. Severely affected areas will thin out as the grass blades wither and die. The turf will also have a brownish appearance.

Gray leaf spot is a fungus that survives as mycelium (pictured below) in the early mornings on the infected plant material. Spores are produced during hot, humid weather and spread by wind, watering, and mowing. 


Gray leaf spot is most severe during prolonged rainy, humid, hot periods - usually occurring in early summer when temperatures are between 80 to 90 degrees. High water-soluble nitrogen levels will favor the disease activity along with other factors that may stress the lawn, such as improper mowing and watering or poor soil conditions.


  • Weed Man North DFW's exclusive brand of 65% slow release nitrogen fertilizer feeds your lawn as it needs it through the root; this will help ensure healthy turf and reduce future problems. Most fertilizers sold over the counter contain a lower amount of slow release nitrogen and a higher amount of water-soluble nitrogen, which can accelerate disease problems in your North Texas lawn.
  • Watering properly is extremely important for reducing the potential occurrence of this turf damaging disease. Avoid watering in the early evening during hot, humid weather, as this extends the leaf wetness period and can lead to a greater chance of gray leaf spot disease.
  • Do not water the lawn in the Spring until the seasonal rains have ended, waiting until it has been more than one week since the last rainfall before watering the lawn.
  • Allow for air movement and light penetration by pruning back any trees and undergrowth.
  • Always use a sharp mower blade, as this will allow the turf blade tips to heal quickly.
Follow Weed Man North DFW's Mowing and Watering tips to help reduce the likelihood of gray leaf spot disease.

Weed Man North DFW Can Help 

Your Weed Man North DFW team is here to help. Weed Man's turf specialists can recognize Gray Leaf Spot and make recommendations on other treatments or changes to cultural practices that may be necessary to help your North Texas turf remain healthy and vigorous.